150-year-old Sydney tree under threat as removal begins

Environmentalists will rally outside Malcolm Turnbull's Sydney office against the removal of a 150-year-old Moreton Bay Fig known as the "Tree of Knowledge".

Arborists began chopping down the historic tree in Randwick on Sunday night to make way for a CBD light rail project that will run near the University of NSW.

Green MP Mehreen Faruqi has told ABC Radio the tree is "irreplaceable" and he's urging people to meet outside the prime minister's office on Monday morning.

A group of about 40 gathered on the corner of Wansey Road and High Street, where the tree stands, after construction began, looking on from behind two-metre-high fencing.

Randwick City councillor Kathy Nielson, who has fighting for months to save the tree, keeping a dialogue going between Randwick City Council, the University of NSW and Transport for NSW, said she was of the understand Transport for NSW was still considering its options.